A federal magistrate has overturned a Marin County man's conviction for a murder he committed as a teenager in 1982 that was linked to Pendragon, another man's bizarre plot to take over the county and rule it as King Arthur.

Crossan Hoover, now serving 26 years to life in prison, might well have been found insane if jurors had been given a proper legal definition of insanity, and if prosecutor Edward Berberian - now the county's district attorney - hadn't withheld key information from a psychiatric witness, said U.S. Magistrate James Larson.

The ruling, issued Sept. 7, entitles Hoover to a new trial. His lawyer, Nina Wilder, said Thursday she hopes the county will instead drop the case and allow his release from Solano State Prison, where she said he has been a model inmate with no evidence of lingering psychiatric problems.

Berberian said Thursday he was unaware of the ruling and had no immediate comment.

Hoover was 17 when he killed Richard Baldwin, 36, owner of a car restoration shop in San Rafael, by beating him in the head with a baseball bat and stabbing him in the chest with a chisel. Hoover, another youth and their employer, Mark Richards, then took cash and other items from Baldwin's home, put his body in a motorboat, and dumped it in San Francisco Bay.

Richards, a 29-year-old contractor who employed the youths as construction workers, had told them of his plan to take control of Marin County in a paramilitary coup, blow up the connecting bridges and install laser guns on Angel Island and Mount Tamalpais to guard his kingdom. He ran into financial troubles in 1982 and enlisted the youths to kill his friend, Baldwin, to get money, promising Hoover $5,000, according to court records.

Richards was convicted of murder in a separate trial and sentenced to life without parole.

State courts upheld Hoover's conviction, but Larson said the jury's sanity verdict was tainted by flawed jury instructions and the prosecutor's withholding of evidence from a psychiatrist.

Medical witnesses for the defense said Hoover had been prone to psychotic and violent outbursts, hallucinations and suicidal impulses, making him vulnerable to Richards and the Pendragon fantasy. In his ruling, Larson said Hoover's disconnection with reality was illustrated by his testimony that he had repeatedly clubbed Baldwin with the bat, then stabbed him in the eye because he was still talking, an account that was contradicted by the autopsy.

But a court-appointed psychiatrist, John Buehler, examined Hoover and testified that he was polite and cooperative, showed no signs of delusions, and had killed Baldwin for money. Larson said the testimony was critical to the prosecution's case that Hoover was sane, along with the defendant's statement to a psychologist that he had known the killing was wrong but wanted the $5,000 offered by Richards.

The magistrate said jurors probably would have found Hoover insane if they had been told that a defendant who hadn't understood the nature of his actions was legally insane. The state Supreme Court ruled in another case, a year after Hoover's trial, that such a definition was required. Larson said the sanity case was also marred by Berberian's withholding of evidence from Buehler.